Dry cooling system using thermally induced vapor polymerization

ABSTRACT

A system and method for providing dry cooling of a coolant in a directed energy system, having a plurality of heat exchangers which depolymerize and polymerize a polymer. Specifically, the depolymerization process is endothermic and draws heat from a source liquid in a first heat exchanger, and the polymerization process is exothermic and expels heat from a second heat exchanger. Additional heat exchangers and holding tanks may be incorporated in the system and method. Pumps having adjustable volumetric flow may be incorporated and provide customized cooling and energy draw.

BACKGROUND OF THE INVENTION

The disclosed technology regards a cooling system which can function toprovide power plant condensers with cooling water at desirabletemperature levels to maintain turbine power production at optimumthermal efficiency levels. The technology may also replace the powerplant condenser, and provide the power plant low-pressure-turbine withreturn water at temperatures to achieve the turbine's designed optimumback pressure at any ambient conditions. The disclosed technologyfurther relates to an improvement in dry cooling systems to overcome theinherent thermodynamic performance penalty of air-cooled systems,particularly under high ambient temperatures. The disclosed technologyhas other applications, including providing cooling and heating in airconditioning systems, and generally in the removal of heat from liquidsources in a controlled environment, as well as streams or other watersources in the natural environment. Using the methods of the technology,heat generated by the system may also be used to warm an environment oranother liquid source.

The disclosed technology further regards a cooling system which can beintegrated with the thermal management system of directed energy systemssuch as high energy lasers (HELs). By means of a coolant, the thermalmanagement system of an HEL absorbs heat generated by the pump diodesand other HEL components, and the disclosed technology is effective inwithdrawing heat from the coolant, thereby facilitating continuousoperation of the HEL.

More than 86% of electricity in the United States of America is producedby thermoelectric power generating plants, most of which use coal,natural gas, or nuclear fuel to generate thermal energy. As shown inFIG. 1, the thermal energy produces superheated steam in theboiler/steam generator, which drives a steam turbine to produceelectrical power by the generator. Each power plant is designed for theconditions of its particular geographic location, which conditionsimpact the design point of the low pressure turbine exhaust pressure.The exhausted steam coming out of the turbine last stage is condensed ina condenser by cooling heat transfer with the condenser, then pumpedback to the boiler as boiler return water, and the process is repeated.Although unique to each plant, the return condensate water ranges intemperature from 35° C. to 52° C.

The pressure of the outlet steam causing the turbine blade rotation,called back pressure, is defined by the condenser temperature. For drycooling systems, the condenser temperature is a strong function of theambient temperature. Therefore, an increase in ambient temperaturedirectly affects the power plant efficiency. For indirect coolingsystems, the ambient air increases the cooling water temperature whichin turn increases the condenser temperature. However, for direct aircooled systems the condenser temperature is directly influenced by theambient temperature.

Typically, more than 60% of the original energy generated by the steamgenerator/boiler is wasted and carried away as low-grade heat by theplant condenser cooling water or directly dissipated to the ambient air.Operators must remove this heat, and 99% of baseload thermoelectricplants in the United States of America use water-cooled systems, or wetcooling, to remove the heat from the condenser cooling water. Powerplant operators prefer wet cooling over dry-cooling systems becauseambient water temperatures tend to be cooler and more stable thanambient air temperatures; further, water evaporation allows foradditional cooling capacity, enabling more cost-effective rejection ofheat. However, the wet cooling processes lead to a significant amount ofwater loss, with power plants using wet-cooling systems currentlyaccounting for 41% of all fresh water withdrawals in the United Statesof America.

Availability of fresh water resources is increasingly strained bydrought and growing demands, and potential climate change impacts adduncertainty to the quality and quantity of future water supplies.However, while dry-cooling technologies do not result in significantwater use, because of their sensitivity to ambient air temperaturescurrent dry-cooling technologies drive down the overall efficiency ofpower generation compared with the efficiency of wet cooled condensers.Therefore, there is a need for a dry-cooling technology that eliminateswater loss or the dependency on water while maintaining the highoperating efficiencies of electric power generation presently achievedby wet-cooling technologies.

Power plant condenser cooling is divided into five main technologyareas, which differ greatly in the amounts of water consumed: (1)once-through cooling; (2) closed-cycle wet cooling; (3) cooling ponds;(4) dry cooling; and (5) hybrid cooling.

Once-through cooling systems withdraw cold water from, and return heatedwater to, a natural body of water such as a lake, a river, or the ocean.In operation, the source water is pumped through the tubes of a steamcondenser. As steam from the turbine condenses on the outside of thetubes, the heat of condensation is absorbed by the source water flowingthrough the tubes. The source water exiting the condenser, warmed by 15°F. to 30° F. depending on system design, is discharged to the originalsource. The amount withdrawn varies from 25,000 to 50,000 gallons/MWh.Although none of the water is consumed within the plant, someconsumptive loss results from enhanced evaporation from the surface ofthe natural body of water due to the heated water discharge. The lossdue to this enhanced evaporation is not well known and is expected to besite-specific, but it has been estimated as 0.5% to 2% of the withdrawnsource water amount, or 125 to 1000 gallons/MWh. The biggest drawback ofonce-through cooling systems is that heated discharges may degrade thenatural body of water, increasing the overall water temperature of thenatural body of water. The thermal pollution is most significant whenthe source of the water is a river or other body with limited volume,where the water withdrawn and discharged is a significant portion of thenatural water flow.

Closed-cycle wet cooling is similar to once-through cooling in that ascold source water flows through the tubes of a steam condenser, steamfrom the turbine condenses on the outside of the tubes. However, insteadof returning the heated condenser water to its source, it is pumped to awet cooling device such as a cooling tower, cooling pond, or coolingcanal, where it is cooled by evaporation of a small portion of the waterto the atmosphere to within 5° F. to 10° F. of the ambient wet-bulbtemperature. Makeup water is added to compensate for the water loss dueto evaporation and the again cooled water is then recirculated to thesteam condenser.

Wet cooling devices used in closed-cycle wet cooling transfer thermalenergy from heated cooling water to the atmosphere through both heattransfer to the ambient air and evaporation, to bring the cooling waterto near wet-bulb air temperature. Specifically, as ambient air is drawnpast a flow of cooling water, a small portion of the water evaporates,and the energy required to evaporate that portion of the water is takenfrom the remaining mass of water, thus reducing its temperature. About970 Btu of thermal energy is absorbed for each pound of waterevaporated.

To achieve better performance, heated cooling water may be sprayed to amedium, called fill, to increase the surface area and the time ofcontact between the air and water flow. Some systems use splash fill,which is material placed to interrupt the water flow causing splashing.Other systems use film fill, which includes thin sheets of material(usually PVC) upon which the water flows, enhancing evaporation.

Cooling towers draw air either by natural draft or mechanical draft, orboth. Natural draft cooling towers utilize the buoyancy of warm air, anda tall chimney structure. In this structure the warm, moist airnaturally rises due to the density differential compared to the dry,cooler outside air, producing an upward current of air through thetower. Hyperbolic towers have become the design standard for naturaldraft cooling towers due to their structural strength and minimum usageof material. The hyperbolic shape also aids in accelerating air flowthrough the tower, and thus increases cooling efficiency. Mechanicaldraft towers use motor-driven fans to force or draw air through thetowers, and include induced draft towers which employ a fan at the topof the tower that pulls air up through the tower (as shown in FIG. 1),and forced draft towers which use a blower-type of fan at the bottom ofthe tower, which forces air into the tower.

Cooling ponds are man-made bodies of water which supply cooling water topower plants, and are used as an effective alternative to cooling towersor once-through cooling systems when sufficient land, but no suitablenatural body of water, is available. The ponds receive thermal energyfrom the heated condenser water, and dissipate the thermal energy mainlythrough evaporation. The ponds must be of sufficient size to providecontinuous cooling, and makeup water is periodically added to the pondsystem to replace the water lost through evaporation.

Current dry cooling systems can be a direct system, in which turbineexhaust steam is condensed in an air-cooled condenser (ACC), or anindirect system, in which the steam is condensed in a conventionalwater-cooled condenser. For indirect systems, the heated cooling wateris circulated through an air-cooled heat exchanger before returning tothe water-cooled condenser. In the direct system, the steam is condensedin the ACC in finned tube bundles (galvanized steel tubes with aluminumfins), and the heat is dissipated directly to the ambient air. Directand indirect cooling systems operate without water loss (other than asmall amount of water used to periodically clean the air-side surfacesof the air-cooled condenser or heat exchanger). The condensingtemperature, in the case of direct dry cooling, or the cold watertemperature, in the case of indirect dry cooling, is limited by theambient air temperature, which is always higher than the ambientdry-bulb temperature. Although dry cooling achieves significant watersavings, the capital and operating costs are much higher than they arefor closed-cycle wet cooling, and the physical footprint is larger.Furthermore, plant performance is reduced in the hotter times of theyear when the steam-condensing temperature (and hence the turbineexhaust pressure) is substantially higher (being limited by ambient airtemperature) than it would be with wet cooling.

Another dry cooling system is the Heller System, which uses a directcontact condenser instead of a steam surface condenser. In this systemthe turbine exhaust steam is in direct contact with a cold water spray,and no condenser tubes are used. The resulting hot condensate and watermixture are pumped to an external air-cooled heat exchanger. Theair-cooled heat exchanger may have a mechanical draft design, a naturaldraft design or a fan-assisted natural draft design. The direct contactcondenser has the advantage of lower terminal temperature difference(TTD, which is the temperature difference between the saturation steamtemperature and the cooling water outlet temperature), and thus lowersturbine back-pressure.

Hybrid cooling systems have both dry and wet cooling elements that areused alternatively or together to achieve the best features of eachsystem. In a hybrid cooling system a power plant can achieve the wetcooling performance on the hottest days of the year, and the waterconservation capability of dry cooling at other times. The wet and drycooling components can be arranged in series, or in parallel, and may beseparate structures or integrated into a single tower. The dry coolingsystem elements can be either direct or indirect types. The most commonconfiguration for hybrid cooling systems to date has been parallel,separate structures with direct dry cooling.

Like the wet cooling systems described hereinabove, the wet coolingelements of a hybrid system use significant amounts of water,particularly during the summer months. Therefore, it is most suitablefor sites that have significant water availability but not enough forall-wet cooling at all times of the year. For sites where water use ishighly limited or contentious, even the use of 20% of the all-wetamounts might be unacceptable, requiring all-dry cooling to allow theplant to be permitted. For sites with adequate water, the performanceand economic advantages of all-wet cooling systems are significant. Insome cases, plant siting might be eased by evidence of “responsiblecitizenship,” in which by means of a hybrid cooling system a plantdeveloper offers some degree of reduced water use to the local communityconcerned about water for agriculture, recreation, or industry.

The disclosed technology overcomes the aforementioned problemsassociated with power plant condenser cooling. A broad object of thedisclosed technology is to provide a novel method and apparatus forremoval of waste heat from power plant condensers with high overallprocess thermal efficiency and without water waste.

Another object of the disclosed technology is to provide for power plantcooling in a relatively compact apparatus, by maximizing the thermalcapacities of the apparatus. A further object of the disclosedtechnology is to provide a dry cooling system and method of dry coolingfor effective heat removal or heat generation, operating at a highcoefficient of performance.

In another field of innovation, the thermal management system (TMS) fordirected energy systems such as high energy lasers (HELs) absorbs heatgenerated by the pump diodes and other HEL components and rejects it tothe environment, thereby preventing the HEL from overheating andenabling it to operate continuously. Because HELs generate a significantamount of heat, TMSs capable of providing a sufficient level of coolingto dissipate this heat continuously are very large, heavy, and consume asignificant amount of electricity. For example, a 100 kW HEL with 20%electro-optical efficiency would require a TMS that provides 400 kW ofcooling. Thus, if the TMS is a chiller with a coefficient of performanceof 4, then 100 kW of electricity would be required just to operate theTMS. This significant power consumption competes with the availableelectricity required to operate the HEL. Therefore, there is a need fora TMS that allows continuous HEL operation, but also has a very lowSize, Weight, and Power (SWaP). The disclosed technology and methodsprovides an effective thermal management system for directed energysystems such as HELs, allowing for continuous operation of the HEL,while maintaining a very low SWaP.

SUMMARY OF THE INVENTION

In accordance with the above objects, the disclosed technology relatesto cooling systems and methods which function to provide power plantcondensers with return water at the necessary temperature levels tomaintain power production at their optimum thermal efficiency levels.Optimum condenser temperature varies depending on the power plant'sdesign and its geographic location. Condenser temperature design forcombined cycle and steam power plants ranges between 35-52° C. Ashereinabove discussed, the condenser's ability to lower supplywater/condensate temperature determines the back pressure for thelow-pressure steam turbine, wherein an increase in condenser temperatureincreases the back pressure on the turbine blades, leading to reducedpower plant efficiency.

The disclosed technology may also replace the power plant condenser, orbe used to improve other dry cooling systems. The disclosed technologyfurther may be used in other applications, such as providing cooling andheating in air conditioning systems, and generally in the removal ofheat from waste/stream heat sources.

The disclosed technology is specifically useful in a power plant's drycooling system, using the depolymerization of a polymer over a catalystin a closed system, including in liquid communication a plurality ofheat exchangers configured to form depolymerization and polymerizationassemblies. In some embodiments a cold energy storage assembly is alsoprovided.

The depolymerization process and assembly of the disclosed technologydepolymerizes a polymer over a catalyst, resulting in a monomer richvapor or a polymer-monomer liquid (as described in the embodimentsbelow). This depolymerization process is an endothermic reaction,drawing heat from the source water (e.g., condenser water or steamexiting the low pressure turbine, last stage) flowing through the heatexchanger in a depolymerization cooling unit (DCU).

The monomer rich vapor or the polymer-monomer liquid is then transferredto the polymer separation unit (PSU), where the monomer rich vapor isseparated from the polymer-monomer liquid. The monomer rich vapor isconveyed to the polymerization assembly, reacting over an acid catalystbed in a polymer heating unit (PHU) to convert the monomer back to theoriginal polymer in liquid phase. The polymerization process is anexothermic reaction, and heat generated may be expelled from the heatexchanger vessel of the polymerization assembly by, for example, aircooled or liquid cooled processes. In some embodiments, thepolymerization assembly employs the dry cooling approach to expel heatfrom the PHU, using air cooled heat exchangers. In other embodiments,the heat generated from the polymerization process of the disclosedtechnology is transferred to and used by another subprocess of thetechnology. To complete the cycle, the polymer stream is pumped by aliquid pump back to the DCU to provide below ambient wet bulbtemperature cooling for a standalone cooling system.

To achieve continuous operation with high conversion efficiencies, thesystem may include one or more polymer separation units (PSU), wherebyusing heat from an independent stream of source liquid, ambient air orheat generated from the polymerization process, the monomer vapor richmixture (or polymer-monomer liquid) from the DCU and/or the polymer richliquid mixture from the PHU are further separated into two streams: avaporous light monomer rich stream and a liquid polymer rich stream. ThePSU(s) thereby creates a buffer between the DCU and the PHU. In someembodiments a single PSU is placed downstream of the DCU and downstreamfrom the PHU, enhancing polymer/monomer separation from each assembly.In another embodiment, a first PSU can be placed downstream of the DCU,enhancing polymer-monomer separation from the DCU product vapor stream,and a second PSU is placed downstream of the PHU, enhancingpolymer-monomer separation from the PHU product liquid stream. In athird embodiment, the PSU and PHU are configured so that heat generatedfrom the PHU is transferred to the PSU, such as in a combinedpolymerization and separation unit as hereinafter described. In theseand similar configurations, the light monomer-rich stream from thePSU(s) is circulated into the PHU for further polymerization reaction,while the polymer-rich liquid stream from the PSU(s) is circulateddirectly to the DCU for depolymerization, or collected in a holding tankfor later circulation through the DCU.

To provide cooling below ambient wet bulb temperatures during hot summerdays with temperatures higher than the saturation temperature at steamturbine back pressure, the elevated temperature polymer produced in thePHU may be stored in a cold energy storage assembly, having a daystorage tank (DST) which stores the elevated temperature polymer fromthe PHU (or the PSU). In the evening, the elevated temperature polymercycles through a polymer cooling heat exchanger unit (PCU), dissipatingits sensible heat into the cooler evening ambient air. The lowertemperature polymer may then be stored in a cold energy storage tank(CST), where it waits for reuse the next day by pumping the liquidpolymer to the DCU, and the cycle is repeated.

In some embodiments, water is incorporated into thedepolymerization/polymerization cycle of the disclosed technology,partially vaporizing in the DCU with the depolymerization of thepolymer, and condensing in the PHU with the polymerization of themonomer.

For optimal performance, the polymer should be selected based on thetemperature range in which it depolymerizes and polymerizes, wherein inthe power plant condenser cycle the temperature range ofdepolymerization is comparable with the power plant's cooling systemoperating temperatures, and the temperature range of polymerizationexceeds the hottest ambient air summer temperatures at the site. Othertemperature ranges may be suitable in other applications, and thereforeother polymers may be more suitable.

In an exemplary embodiment of the disclosed technology, the liquidpolymer is paraldehyde, which is depolymerized in the DCU into the lightmonomer acetaldehyde over an acid based catalyst. The acetaldehyde richvapor, having a small amount of paraldehyde gas, is actively removedfrom the DCU as vapor using a blower, compressor or vacuum pump. Thisactive removal of acetaldehyde rich vapor allows the paraldehyde to bedepolymerized beyond its chemical equilibrium. The depolymerization andresulting vaporization process are endothermic, resulting in heatabsorption from the source liquid flowing through the heat exchanger ofthe DCU. The maximum coolant specific energy, estimated based on 100%depolymerization conversion, is 1,434 kJ/kg. In practical operation, thedepolymerization process can be controlled by varying operatingparameters with high conversion up to 95%, providing a coolant specificenergy up to 1,363 kJ/kg to meet cooling needs. This practical coolantspecific energy is up to 4 times of the latent heat storage capacity ofice.

In another exemplary embodiment of the disclosed technology, the liquidpolymer is paraldehyde, which is depolymerized in the DCU over an acidbased catalyst into a liquid mixture of polymer paraldehyde and monomeracetaldehyde at its chemical equilibrium. The liquid mixture then entersthe PSU, whereby heat is used to separate the liquid mixture intoparaldehyde rich liquid and acetaldehyde rich vapor streams. Using ablower, compressor or vacuum pump, the acetaldehyde rich vapor stream isthen received by and regenerated in the PHU as described in the aboveembodiments. The paraldehyde rich liquid remaining in the PSU andresulting from the regeneration in the PHU, is returned to the DCU torepeat the process. Like the vaporization embodiment above, thisdepolymerization process is endothermic, resulting in heat absorptionfrom the source liquid flowing through the heat exchanger of the DCU.The maximum coolant specific energy depends on the reaction equilibrium,and is estimated from 36.4 to 191.2 kJ/kg at the temperature range from4 to 45° C. Although the practical specific energy is lower than theprevious embodiment, the cooling rate can be adjusted by regulatingpolymer feed rate to meet the cooling needs. For example, at a 1 kg/minpolymer feed rate, the DCU of this embodiment can provide between 0.61and 3.2 kW cooling at temperature range between 4 and 45° C.

The monomer conversion of acetaldehyde in the polymerization process ofthe PHU is typically between 60-80%, depending on the processtemperature (e.g., ambient air temperature for an air cooled heatexchanger). However, as hereinabove discussed remaining light and liquidmonomer can be separated from the polymer rich liquid in the PSU, andexcess light monomer can be recycled back to the polymerizationassembly. With this recycling, the overall monomer conversion may reach95%. Thereby, the exothermic process has polymerization conversions thatmatch the depolymerization conversions for the endothermic process,allowing the cycle to be operated continuously and efficiently as a heatpump cycle by removing heat from the cooling process, and rejecting thatheat from the heating process, with overall coolant energy density up to1,363 kJ/kg.

The disclosed technology further provides a process for an efficient drycooling system to dissipate low quality heat from chemical, mechanical,thermal, or power plant operations. It can work as a standalone system,or be synchronized with other dry cooling units. Further, it iscontemplated that the exothermic polymerization process may be used as aheat source for other processes or purposes, such as for example adistillation unit.

The cycle of the disclosed technology operates based on chemical heatpump fundamentals and utilizes chemical thermal energy storage.Therefore, when the chemical potential is fully utilized and the polymeris allowed to be fully depolymerized into acetaldehyde vapor, it is moretolerant to ambient temperature fluctuation than traditional dry coolingtechnology such as air cooled heat exchangers. For example, at anambient temperature of 45° C., air cooling of a 45° C. water stream isimpossible since there is no driving force for the heat transfer betweenwater and air. With the cycle of the disclosed technology at the sameambient temperature condition, the endothermic process will lower thecoolant/polymer temperature, allowing heat transfer between the waterand the coolant. Using paraldehyde as the polymer, even under conditionswhen the coolant/polymer is fed at temperatures higher than the hottestambient temperatures, the coolant performance will observe less than1.4% performance penalty per 10° C. increase in polymer temperature.This behavior is caused by the small ratio between the paraldehydesensible heat capacity and the overall reaction specific enthalpychange. Specifically, the sensible heat capacity for paraldehyde is 0.27kJ/mol/C; therefore, the sensible heat storage for 10° C. temperaturechange is only 2.7 kJ/mol, which only accounts for 1.4% of totalreaction heat (189.5 kJ/mol). For example the increase in the polymertemperature from 25-35° C. reduces the DCU cooling capacity by 1.4% (apolymer feed at 25° C. gives a DCU cooling capacity of 1 kW; when itstemperature increases to 35° C., its cooling capacity is reduced to0.986 kW). Similarly, the monomer will regenerate in the polymerizationprocess with a process temperature higher than the ambient 45° C.temperature, allowing heat to be rejected to the environment using atraditional air cooled heat exchanger. Thus, the monomer-vapor cycle ofthe disclosed technology allows the system to provide efficient coolingat high ambient temperatures, when traditional dry cooling methods fail.

Furthermore, directed energy systems such as high energy lasers (HELs)are often designed with a thermal management system (TMS) to operatewithin a specific temperature range, where diode efficiency is highest,allowing maximum conversion of input energy into directed energy.Therefore, manufacturers may specify a coolant flow rate range andtemperature range in the TMS to ensure the temperature of the diode andother components of the HEL are maintained close to the optimaltemperature. The disclosed technology cycle, systems and methods can beused to provide highly efficient cooling to this coolant, ensuring itreturns to the directed energy components within the specifiedtemperature and flow rate ranges. By this configuration, the HEL has avery low SWaP capable of continuous operation.

BRIEF DESCRIPTION OF FIGURES

Embodiments of the invention will now be described in conjunction withthe accompanying drawings, where:

FIG. 1 is a flow diagram of a prior art thermoelectric coal or naturalgas fire steam power plant, using a cooling tower wet cooling system.

FIG. 2 is a flow diagram of a thermoelectric coal or natural gas firesteam power plant, including an embodiment of the apparatus of thedisclosed technology in an indirect dry cooling configuration.

FIG. 3 is a flow diagram of a thermoelectric coal or natural gas firesteam power plant, including an embodiment of the apparatus of thedisclosed technology in a direct dry cooling configuration.

FIG. 4 is a schematic process flow diagram of an embodiment of theapparatus of the disclosed technology, using cold energy storage.

FIG. 5 is a schematic process flow diagram of another embodiment of theapparatus of the disclosed technology as an uninterrupted cooling cycle,without cold energy storage.

FIG. 6 is a schematic process flow diagram of another embodiment of theapparatus of the disclosed technology, using an uninterrupted heatpumpin the cooling cycle.

FIG. 7 is a schematic process flow diagram of the embodiment of FIG. 6,in the heating cycle.

FIG. 8 is a schematic process flow diagram of an embodiment of theapparatus of the disclosed technology, using two PSUs.

FIG. 9 is a schematic process flow diagram of another embodiment of theapparatus of the disclosed technology, cofeeding water and polymer fromthe top of DCU.

FIG. 10 is a schematic process flow diagram of another embodiment of theapparatus of the disclosed technology, using an uninterrupted heatpumpin the cooling cycle.

FIG. 11 is a schematic process flow diagram of the embodiment of FIG.10, in the heating cycle.

FIG. 12 is a schematic process flow diagram of another embodiment of theapparatus of the disclosed technology, using an uninterrupted cycle anda combining the PHU and PSU into one combined polymerization andseparation unit (CPSU).

FIG. 13 is a schematic process flow diagram of another embodiment of theapparatus of the disclosed technology, feeding polymer from the bottomof the DCU with water feeding into the DCU from the top.

FIG. 14 is a schematic process flow diagram of another embodiment of theapparatus of the disclosed technology, wherein an embodiment of thedisclosed technology is integrated into a directed energy system toprovide cooling to directed energy components.

FIG. 15 is a schematic process flow diagram of another embodiment of theapparatus of the disclosed technology of FIG. 14.

FIG. 16 is a block diagram for controlling operation of the apparatus ofthe disclosed technology.

FIG. 17 is an exemplary embodiment of a user interface useful incontrolling the apparatus of the disclosed technology.

FIG. 18 is a flowchart of an embodiment of controlling the apparatus ofthe disclosed technology.

DETAILED DESCRIPTION

The features and principles of the disclosed technology are described indetails and through embodiments below, with reference to the indicatedfigures. The particular embodiments of the disclosed technology arepresented as examples, and should not be understood as limitations ofthe claimed inventions. The novel features of the disclosed technologycan be employed as numerous embodiments within the scope of thedisclosed technology. Additional heat exchangers, pressure regulatingcontrol devices, and other ancillary equipment necessary for operationof the disclosed technology in accordance with the teachings of thisdisclosure, the use of which are well known in the art, are not shown inthe schematic figures. A person skilled in the art may readily see thatvarious configurations of heat exchangers, pumps, blowers and otherstandard processing equipment may be employed to achieve desired processstream temperatures and pressures, while maximizing the overall processthermal efficiency.

The present technology uses a depolymerization and polymerizationthermochemical cycle to provide dry cooling to a condenser or otherwater source, eliminating water losses and maintaining power plantthermal efficiency even during the hottest time of the year. One ofpolymers suitable for use in the disclosed technology is paraldehyde,which depolymerizes to the monomer acetaldehyde. Other systems may usepolymers with higher depolymerization temperatures when appropriate forpurposes of the system, for example when the system is used to cool lowquality waste heat streams (<200° C.).

The disclosed technology uses polymerization [paraldehyde(Pa(l):C₆H₁₂O₃(l)], depolymerization [acetaldehyde (A(l):CH₃CHO)] andvaporization [acetaldehyde ((A(g):CH₃CHO))] thermochemical reactionscycle for cooling purposes. The equations representing the chemicalreaction of the depolymerization of paraldehyde and vaporization ofacetaldehyde are indicated in equations 1 and 2:C₆H₁₂O₃(l)↔3CH₃CHO(l), ΔH_(298K)=110.3 kJ/mol  (1)3CH₃CHO(l)↔3CH₃CHO(g), ΔH_(298K)=79.2 kJ/mol  (2)The net reaction is then:C₆H₁₂O₃(l)↔3CH₃CHO(g), ΔH_(298K)=189.5 kJ/mol  (3)

One mole of liquid paraldehyde is depolymerized over an acid catalyst,into three moles of gaseous acetaldehyde. The depolymerization reactionis endothermic with a net reaction heat of 189.5 kJ/mol (as the sum ofreaction heat and vaporization heat).

The system of the disclosed technology utilizes the high reaction heatof the depolymerization of paraldehyde for cooling a source liquid. Withits net reaction heat of 189.5 kJ/mol, the heat capacity of the systemcan be calculated by equation 4, where 132.16 g/mol is the paraldehydemolecular weight.

$\begin{matrix}{{189.5\mspace{20mu}{\frac{kJ}{mol} \div 132.16}\mspace{20mu}\frac{g}{mol} \times 1000\mspace{14mu}\frac{g}{kg}} = {1,434\mspace{14mu}\frac{kJ}{kg}}} & (4)\end{matrix}$

The 1,434 kJ/kg is the maximum theoretical cold energy storageachievable. The depolymerization processes operate in the temperaturerange of 4-45° C., under pressure applied in a range of 3-14.7 pound persquare inch absolute (psia); in the embodiments hereinafter described,pressure from a blower or vacuum pump is applied in the range of 3-12psia.

Although the depolymerization reaction is reversible, it can be promotedby the removal of the monomer, such as by means of vaporization.Specifically, in a typical depolymerization reaction without the activeremoval of light monomer, the reaction will start first bydepolymerizing the polymer to produce light monomer. However, becausethis is a reversible reaction, as the polymer is being depolymerized,the produced light monomer will try to convert (re-polymerize) back tothe polymer. The depolymerization and re-polymerization rates depend onthe concentration of the polymer and the light monomer in the liquid ata given temperature and pressure. In general, higher concentrations willresult in a faster reaction rate. Therefore, high polymer concentrationwill lead to a high depolymerization rate and high light monomerconcentration will lead to a high re-polymerization rate. Eventually,both polymer and light monomer concentrations in the liquid will reach astate where the depolymerization and re-polymerization rate are equaland the polymer and monomer concentrations will remain constant. Thusthe depolymerization conversion and the coolant specific energy islimited by the reaction equilibrium. The limitation, however, does notlimit the cooling rate as the cooling can also be adjusted by regulatingthe polymer flow rate into the DCU.

At the equilibrium state, the resulting mixture is a liquid and themonomer (having a very low boiling point as compared to the polymer)will slowly evaporate from the liquid mixture. Actively removing themonomer rich vapor from the DCU (by means of a blower, for example)creates a low pressure environment, accelerating the evaporation rate ofthe monomer. As the light monomer concentration decreases (through bothremoval of the monomer and additional polymer feed), thedepolymerization reaction dominates to produce more light monomer toreach the equilibrium.

For example, at 40° C., the equilibrium polymer and light monomerconcentrations are about 80 wt % and 20 wt % in liquid, respectively. Ifpure polymer is fed to the DCU and evaporation is negligible, theoverall depolymerization conversion is calculated based on liquidcomposition (20%). The coolant specific energy calculated based on thereaction heat is 20% of the maximum theoretical cold energy storageachievable or 286.8 kJ/kg. By equalizing the evaporation rate (byremoval of the monomer rich vapor) and the polymer feed rate, theoverall depolymerization conversion is calculated based on the vaporcomposition. If the vapor composition is 90 wt % of light monomer(average light monomer composition under test conditions), the overalldepolymerization conversion is 90%. The coolant specific energycalculated based on the reaction heat is 90% of the maximum theoreticalcold energy storage achievable or 1290.6 kJ/kg. Thus, by active removalof the monomer from the reaction tank the overall depolymerizationconversion and the coolant specific energy are significantly higher thanthe equilibrium conversion.

After depolymerization, acetaldehyde gas can be re-polymerized toparaldehyde liquid over an acid catalyst. The polymerization process(acetaldehyde to paraldehyde) operates in the temperature range of26-55° C., under pressure ranges from 10 to higher than 14.7 psia; inthe embodiments herein described, pressure from a blower is applied inthe range of 10-25 psia.

Shown in FIGS. 2-4 are schematic process flow diagrams of embodiments ofthe disclosed technology, including an apparatus that includes coldenergy storage, having three distinct assemblies in liquidcommunication: a depolymerization assembly 100, a polymerizationassembly 200, and cold energy storage assembly 300. In these embodimentsthe depolymerization assembly 100 includes a DCU 101, a PSU 102, aliquid pump 103, and a blower 104. The polymerization assembly 200includes a PHU 201. The cold energy storage assembly 300 includes a daystorage tank (DST) 301, a polymer cooling unit (PCU) 303 and acold-energy storage tank (CST) 302. Each of the DCU 101 and the PHU 201of the assemblies are configured as heat exchangers, wherein catalyticreactions occur and heat is exchanged. The PSU 102 and the PCU 303 arealso configured as heat exchangers, although no catalytic reaction isintended in these tanks. The DST 301 and CST 302 are all storage tanks,not intended to be significant heat exchangers. The tanks and vesselsshould be made from materials that are compatible with the selectedsystem polymer and its monomer; stainless steel is a suitable materialfor these tanks and vessels. The DCU 101 and the CST 302, and other heatexchanger vessels and tanks of the embodiments of the disclosedtechnology may be wrapped in heat insulation, designed as double walledtanks, or may otherwise be insulated from ambient air conditions.

The configuration of the heat exchanger tanks 101, 102, 201, and 303 maybe independently configured to maximize heat transfer and obtain theright temperature at the flows' exit. The DCU 101 and the PSU 102 areheat exchangers designed to receive source liquid, and transfer heattherefrom to the respective depolymerization and separation reactionswithin the tanks. Liquid to multiphase fluids heat exchangers, such asshell and tube heat exchangers, with straight or coiled tubes, counteror parallel flow, single or double pass, are all suitable heatexchangers to accomplish this heat transfer; other heat exchangers mayalso be suitable for purposes of these reactors of the disclosedtechnology. The DCU 101 includes a de-polymerization chamber and aconduit through which a source liquid cycles, with an acid basedcatalyst in the polymer flow portion of the depolymerization chamber.

The PSU 102 may be a vapor-liquid separator designed with the inletmixtures from the DCU 1003 and the PHU 1009 to be separated to monomerrich vapor 1005 (at this stage, greater than 80 wt % monomer, and insome embodiments greater than 90 wt % monomer gas) and polymer richliquid 1004 (greater than 80 wt % polymer, and in some embodimentsgreater than 90 wt % polymer liquid), under the applications' pressureand temperature conditions. A pressure regulating valve 106 is used tocontrol the amount of mixture from PHU 201 to PSU 102 so that thepressure difference between the two units is properly maintained at theranges described hereinabove. Other vapor-liquid separator designsincluding, but not limiting to, fractionation and distillation columndesign, can also be employed in the PSU to provide high separationefficiency and effectiveness. In some embodiments, a level controlmechanism such as a float level switch is used to allow the accumulationof the polymer rich liquid at the bottom of the PSU; when the level isreached, the PSU outlet port is opened and the accumulated polymer richliquid stream is discharged from the PSU.

The PHU 201 may be configured as an air-to-gas/multiphase heatexchanger, such as a tube and fin heat exchanger, with an acid basedcatalyst in the monomer/polymer flow portion of its polymerizationchamber. The PCU 303 may be configured as an air-to-liquid heatexchanger, such as a tube and fin heat exchanger. Other heat exchangerconfigurations may be suitable for purposes of these reactors of thedisclosed technology.

The embodiment of FIG. 5 includes an uninterrupted cooling cycleapparatus, without cold energy storage. The components and operatingparameters of this embodiment are similar to the components in theafore-described system having cold energy storage, but without the largestorage tanks of the cold energy storage assembly. Specifically, in thisembodiment the rich liquid polymer mixture is stored in a much smallerpolymer storing tank (PST) 105, and then pumped to the DCU 101,providing uninterrupted cooling cycle operations. The PST may be sizedto hold about one-half of the polymer needed for one cycle through thesystem of the present disclosure.

In some embodiments, as shown in FIG. 8, the system comprises two ormore PSUs, for example with a first PSU 102 positioned after the DCU101, receiving streams of monomer rich vapor, and by its heat exchangerconfiguration further separating out monomer gas from polymer gas beforeconveying the vapor to the PHU 201, and a second PSU 202 positionedafter the PHU 201, receiving streams of polymer rich liquid, and furtherseparating out monomer liquid (which evaporates in PSU 202 to monomergas) therefrom before conveying the polymer rich liquid to the PST 105or the DCU 101. The polymer rich liquid from the first PSU 102 and thesecond PSU 202 in this embodiment may then be conveyed to the PST 105for later depolymerization by the DCU, and the monomer gas from thefirst PSU 102 and the second PSU 202 may be conveyed back to the PHU forpolymerization. A second blower 204 may also be provided to activelyremove monomer gas from the PSU 202. In this embodiment, either ambientair or condenser cooling water may be used to supply heat to the PSUs102, 202.

In these embodiments source liquid 1001, 1006, such as coolant water isconveyed to the conduit of the DCU and, in some embodiments the PSU(s),by means of an external pump (not shown), such as the cooling water pumpof the condenser. The flow rate of the source liquid through the heatexchanger tubes can be controlled by means of the pump so that thetemperature of the source liquid upon discharge from the DCU tube isnear or at the optimum temperature of the turbine (35-52° C.).

Inlet and outlet ports or valves may be positioned within the system ofthe disclosed technology to control fluid flow. The pumps used inassociation with or as part of the system of the disclosed technologymay be controlled by a pump control system, which may receive signalsfrom sensors within the DCU and the PSU, for example, and other heatexchangers, tanks and lines of the disclosed technology, to pumpadditional source liquid through the DCU or the PSU, additional polymerinto the DCU, additional monomer rich gas from the DCU, and deliverpolymer liquid to the CST, or from the CST to the PCU, or otherwisecontrol the flow of liquids and vapor through the system of thedisclosed technology to reach the desired source liquid temperature andoptimize operation of the system.

The DCU 101 is an endothermic reactor, with a heat transfer surface (atits tubes, for example) allowing the reaction process in thede-polymerization chamber to absorb heat from the source liquid cycledinto the DCU tubes (conduit) at 1001. The conversion from a polymer to amonomer liquid and the vaporization of the monomer liquid occur over acatalyst in the polymer coolant flow portion of the reactor; becausethis reaction is endothermic, it absorbs a significantly large amount ofheat from the circulating source liquid, at the heat transfer surface.The polymer may be continuously cycled into the DCU vessel at 1008; whenambient temperatures make supplemental cooling desirable, the coolliquid polymer stored in the CST 302 is pumped into the DCU 101 from thestream 1011. A monomer rich vapor mixture is withdrawn from the DCUvessel at 1003, under a low pressure effect provided by the blower 104.This depletion of the monomer in the DCU forces the depolymerizationreaction to promote further polymer depolymerization in reachingchemical equilibrium. For paraldehyde, depolymerization and vaporizationoccurs at any temperature at or above 4° C.; operating temperatures of10-45° C. within the DCU appear to maximize depolymerization andvaporization. Flow rate of the paraldehyde into the DCU at 1008 in therange of 20-39 grams/minute, under pressure in the range of 3-12 psia,results in a cooling rate of 0.3-1.0 kW with a 90 wt % conversionachieved by actively removing monomer vapor, and a cooling rate of0.07-0.2 kW with a 20 wt % conversion without actively removing monomervapor. The temperature of the source liquid as it exits the DCU at 1002may be controlled by the flowrate of the source liquid, the polymer feedrate and the rate of withdrawal of the monomer rich vapor.

In the embodiments shown in FIGS. 2-5, under the influence of blower104, the monomer rich vapor mixture (A(g) and Pa(g)) flows first to PSU102, in stream 1003. The blower applies pressure to the tanks of thedepolymerization assembly (and the cold storage assembly of FIGS. 2-4)in the range of 3-12 psia, to cause monomer gas separation and activeremoval of the monomer rich vapor from each of the DCU and the PSU. Theblower exit pressure is in the range of 10-25 psia, forcing the vapormixture from the PSU to flow into the PHU.

In these embodiments, the PSU 102 also acts as a buffer tank between theDCU 101 and the PHU 201, minimizing the impact of the sudden change inambient conditions on the DCU operation, and allowing the system tooperate continuously with no material imbalance. In the PSU 102, furtherseparation of the monomer gas from the polymer gas occurs, using anindependent stream of source liquid 1006, 1007 as the heat source, andfurther adding more cooling capacity to the system (wherein the streamof source liquid exiting the PSU may be mixed with the cooler sourceliquid exiting the DCU, or may be circulated through the DCU for furthercooling). Specifically, the heat from the source liquid separatesmonomer gas and polymer liquid. The flow of condenser cooling water as asource liquid may be achieved by the condenser pump, and regulated tocontrol the heat provided thereby within the PSU. The separated monomerrich stream then flows to the PHU 201, under the pumping pressures ofthe blower 104, in flow streams 1005 and 1010. The temperature of stream1010 is intended to be close to ambient temperature. In some embodimentsanother heat exchanger is placed before the PHU to cool stream 1010 tonear ambient temperatures, thereby limiting the reaction temperature inthe PHU.

In the PHU 201, the monomer gas (A(g)) is polymerized over an acidcatalyst to a polymer rich liquid (Pa(l)). The acid catalyst ispositioned in the polymerization chamber of the PHU, and may be providedin a spherical (bead) form, packed inside of the heat exchanger as apacked bed reactor. Supporting metal screens or perforated mated platesmay be positioned at both ends of the heat exchanger tube(s) to hold thecatalyst bed in place, while allowing the monomer to flow through thecatalyst bed. In the embodiment, where the polymer is paraldehyde,acetaldehyde is polymerized back to paraldehyde, over a catalyst, at atemperature range between about 40-60° C., and a pressure range between10 and 25 psia.

This polymerization over an acid catalyst is an exothermic process,where the temperature of the monomer and polymer increases above ambienttemperature. Heat is expelled at 1014 from the PHU to the ambientenvironment at a heat transfer surface. In some embodiments the PHU heatexchanger consists of multiple finned tubes, with ambient air beingblown across the surface of the finned tubes. The fins on the tubeincrease heat transfer surface area and allow efficient heat rejectionfrom the PHU to the atmosphere. A fan can be configured to either blowor pull air across the PHU for efficient heat removal at 1014.

In the embodiments shown in FIGS. 2-5, the PHU produces a polymer richliquid mixture which flows back to the PSU 102 in flow stream 1009. Thepressure differential between the PHU 201 and PSU 102 is regulated byblower 104 in the path of flow stream 1005, 1010 as hereinabovedescribed, and through a pressure regulating valve 106 or an orifice, apump, or a combination of all or any of these devices, in the path offlow stream 1009. By means of the circulating plant condenser coolingwater 1006, 1007, the PSU heat exchanger further vaporizes monomer gasfrom the polymer rich liquid mixture, and a more concentrated polymerrich liquid stream is then expelled from the PSU to the DST 301 (or asshown in FIG. 5, directly back to the PST 105 to the DCU 101), in flowstream 1004. In some embodiments (for example, see FIG. 8) a second PSUis provided for this separation of monomer gas from the polymer richliquid mixture, wherein the monomer gas is evaporated from the liquidand recirculated through the PHU 201.

It is noted that the monomer rich gas from the depolymerization assemblycomprises up to 20%, or in some embodiments less than 10%, polymer gas;likewise, the polymer rich liquid from the polymerization assemblycomprises up to 20%, or in some embodiments less than 10%, monomerliquid. The PSU(s) further separate the monomer from the polymer, ineach of these states.

In the embodiment shown in FIGS. 2, 3 and 4, if necessary to cool theliquid polymer at night for next day operation, the liquid polymer isstored in the DST 301 and when the ambient air is cooler is pumped bypump 103 to PCU 303, by stream 1011 to 1012. The PCU 303 cools theliquid paraldehyde using the colder night ambient air, expelling heat at1016. The cooled liquid paraldehyde then flows to the CST 302 forstorage, in flow stream 1013, and is ready for the next day operationand/or conveyance to the DCU by streams 1011 to 1008.

Programmable three-way valves may be used to control the flow pattern ofthe polymer rich liquid through and from the cold energy storageassembly, including for example (a) from the CST 302 to the DCU 101(during the day's high ambient temperature), (b) from the DST 301 to thePCU 303 and CST 302 (during the cooler night ambient temperatures), (c)from the DST 301 to the DCU 101 (when the CST 302 is depleted, or theambient temperature is not too high for the depolymerization reaction),or (d) to control the liquid pump 103 discharge flow either to the DCU101 or PCU 303. Additional valves may be provided throughout the systemto control fluid flow, such as for example, between the PHU and the PSU.

The catalyst within the DCU and the PHU may be the same or differentacid based catalysts (except when used in a heat pump, as hereinafterdescribed, wherein the catalysts must be the same), suitable forpolymerization or depolymerization of the selected polymer. It isbelieved that most strong acid based catalysts would be suitable for usein the process of the disclosed technology. Examples of strong acidbased catalysts suitable for use with the polymer paraldehyde includeperfluorosulfonic acid and sulfonic acid, such as Amberlyst 47,Amberlyst 15, Amberlyst, Amberlite, Amberjet, Purolite, Nafion NR andNickle Sulfate. The catalyst resin (in all or some of the catalytic heatexchangers) may be acid, silica or activated carbon based. Favorablefunctions in a selected catalyst are high reaction rate with theselected polymer and high coefficient of heat transfer. Packingmaterial, such as metal, may be incorporated into the resin bed to allowthe use of less catalyst and maximize the heat transfer area within atank.

As an example, Table 1 indicates the flow rate, temperature, pressure,enthalpy, composition and phases for the streams defined in FIG. 4. Thethermodynamic states were calculated for a 100 MW_(th) cooling plant andrepresent the conditions for steady state operation of the system.

TABLE 1 Comparison of Heat Capacity and Energy Use Units 1011 1008 10031005 1010 1009 1004 1013 1001 1002 Phase [—] Liquid Liquid Vapor SatVapor Sat. Sat. Liq Liq Liq Vapor Liquid Liq. Quality [kg Vap./ 0.0 0.01.0 1.0 1.0 1.0 0.0 0.0 0.0 0.0 kg Liq.] X_(Ac) [massf 0.1 0.1 — — — 0.20.1 0.1 0.0 0.0 liq.] X_(H2O) [massf 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.01.0 liq] Y_(Ac) [massf — — 0.9 0.9 0.9 — — — — — vap] Flow [kg/s] 82.282.2 82.2 95.8 95.8 95.8 82.2 82.2 2,234 2,234 Rates Temp. [° C.] 38.038.0 30.0 30.0 62.0 39.0 40.0 38.0 40.0 30.0 Pressure [psi] 7.4 7.4 7.47.4 13.0 13.0 7.4 7.4 31.5 29.1 Enthalpy ×10³ −5.07 −5.07 −3.94 −3.94−3.90 −5.01 −5.1 −5.1 −15.9 −15.9 [kJ/kg]

FIG. 2 shows a flow diagram of an embodiment of the disclosed technologyas used for cooling the condenser cooling water in a power plant; FIG. 3shows a flow diagram of an embodiment of the disclosed technology asused as the condenser in a power plant.

In another embodiment of the disclosed technology, as shown in theschematic process flow diagram of FIGS. 6 and 7, a reversible heat pumpspace cooling and heating cycle apparatus and method is provided. Inthis embodiment two heat exchangers 401 and 501 are provided todepolymerize and polymerize the polymer/monomer conveyed through thesystem, in the traditional heat pump evaporator assembly 400 andcondenser assembly 500. The components of this embodiment are similar tothe components in the dry cooling embodiment without cold energy storagedescribed above, with an expansion device 408 and several control valves405, 406 and 407, wherein the heat exchanger 401 and the PSU 402 (at2001/2002) are air-to-liquid or to-multiphase heat exchangers.

As shown in FIG. 6, in the cooling mode the heat exchanger 401 of theevaporator assembly 400 functions as a depolymerization cooling unit, inliquid communication with a PSU 402, a polymer storing tank (PST) 403, aliquid pump 404, two two-way automatic control valves 406 and 407, andexpansion valve 408. The automatic control valve 406 provides expansionvalve functions when the flow is directed towards the PSU 402. In thismode the heat exchanger 501 of the condenser assembly functions as thepolymerization heating unit, in liquid communication with a 3-wayautomatic control valve 503. Polymer and its depolymerized monomer flowamong the heat exchangers 401 and 501, with a PSU 402 further separatingthe monomer and polymer, as described in the embodiments above, by flowlines 2003, 2005, 2006-a, 2008, 2004 and 2007-a. A blower, compressor orvacuum-pump 502 is provided to actively remove the monomer gas from theheat exchanger 401 and the PSU 402. The blower, compressor orvacuum-pump 502 further generates the pressure ratio between the secondheat exchanger 501 and the PSU 402. The pressure in the second heatexchanger 501, in the cooling mode, is regulated by a pressureregulating valve, orifice, pump or a combination of all of these devices408. Thereby, as air 2001 flows past the heat exchanger 401 and the PSU402, it is cooled by the depolymerization of the polymer over a catalystand evaporation of the monomer, and transferred to the heat exchanger501 at 2006-a, wherein heat 2011 from the heat exchanger 501 is expelledto the environment.

In the heating mode (shown in FIG. 7), the flow is reversed, and thefirst heat exchanger 401 functions as the polymerization heating unit(providing an exothermic reaction of the monomer over a catalyst), andthe second heat exchanger 501 functions as the depolymerization coolingunit (providing an endothermic reaction of the polymer over a catalyst).Valves 503, 405, 406 and 407 reverse the flow of the polymer/monomer, sothat polymer and monomer flow among the heat exchangers 401 and 501 byflow lines 2004, 2005, 2006-b, 2007-b, 2008 and 2009. The blower 502 isprovided to actively remove the monomer gas from the heat exchanger 501and the PSU 402. In the heating mode, the pressure between the firstheat exchanger 401 and the PSU 402 is regulated through a pressureregulating valve, orifice, pump or a combination of all of these devices408. Thereby, as air 2001 flows past the heat exchanger 401, it isheated by the polymerization of the monomer over a catalyst, and heatfrom the environment 2010 and the PSU 402 at 2002 is drawn in by heatexchanger 501, in its depolymerization endothermic reaction, and coolair is expelled at 2011.

In another embodiment of the disclosed technology, as shown in FIGS. 9and 13, water is incorporated into an uninterrupted cooling cycleapparatus without cold energy storage, similar to the embodiment shownin FIG. 5. In this process water is fed into the system of the disclosedtechnology to inhibit formation of side products or undesired compounds,such as 2-butenal (Crotonaldehyde). 2-butenal is formed by aldolcondensation of acetaldehyde (Ac) where the two acetaldehyde moleculeslink together and form a carbon-carbon bond with the removal of a watermolecule. In the presence of a strong acid catalyst, similar to the acidcatalyst hereinabove described, the acetaldehyde first formsnucleophilic enol, followed by an acid catalyzed dehydration reaction(loss of water molecule) to form 2-butenal. Although the reactionpathway is in favor of the reversible reaction between polymer andmonomer, a small percentage of the 2-butenal can be formed where enoldehydration favors. During the depolymerization of the paraldehyde ofthe methods of the disclosed technology, 2-butenal may be produced as anintermediate species in the formation of the longer chain polymers.These undesired compounds have the potential to reduce the polymercoolant concentration over long-term operation, resulting in a long termcoolant stability issue.

Water was found to be an effective 2-butenal inhibitor in thedepolymerization cycle operation and has low solubility with the polymercoolant. In the present embodiments, adding water content up to 10 wt %reduces 2-butenal concentration to zero. In the embodiment shown in FIG.9, the water is co-fed with the polymer into the DCU 101; in theembodiment shown in FIG. 13, the water is fed into the top of the DCU,and the polymer is fed in the bottom. As shown in the embodiment ofthese Figures, the water and polymer are fed into the DCU 101 byreplacing the PST 105 of the embodiment shown in FIG. 5 with aliquid-liquid separation/storage tank (LST) 107, to facilitateindependent feeding of both water at feed stream 1011, 1012 and polymerat feed stream 1013, 1008 to the DCU 101, by means of liquid pumps 108and 103, respectively, from the LST 107. Water and the polymer arestored in the LST 107 as two distinct layers, with the water layer inthe bottom and the polymer layer in the top of the tank, due to thedensity difference between water and the polymer, and the low solubilityof water in the polymer.

Further, in the embodiment shown in FIG. 9, the system of FIG. 5 isfurther modified so that the water and polymer are co-fed at or near thetop portion of the DCU 101. By such configuration, the accumulation ofwater in the DCU 101 (resulting from the low solubility between thewater and paraldehyde, and the slightly higher density of water thanparaldehyde) is avoided. In the embodiment shown in FIG. 13, only thewater is fed at or near the top portion of the DCU, wherein the excesswater accumulating at the bottom of the DCU is removed via stream 1015.These configurations further allow for optimum depolymerization rates,higher chemical conversion, and higher cooling rate.

In the embodiment of FIG. 9, when operating in a cooling process boththe polymer and the water are pumped from the LST 107 to the top of theDCU 101, entering the DCU as a combined stream of water and polymer. Inthe embodiment of FIG. 13, when operating in a cooling process thepolymer is pumped from the LST 107 to the bottom of the DCU 101, and thewater is pumped from the LST to the top of the DCU. In each embodimentthe polymer is pumped in stream 1008, and the water is pumped in stream1012. The pumping rates of the two pumps 103 and 108 are controlled tomaintain appropriate water content in the DCU by up to 10 wt %, and inthe embodiment of FIG. 9, to produce a uniform mixture of water andpolymer. In the embodiment of FIG. 13, excess water may be removed fromthe DCU by stream 1015, and returned to the LST 107 for recyclingthrough the system (the water having a different density than thepolymer, allowing for removal of the water separate from the liquidpolymer).

As in previously described embodiments of the disclosed technology, thepolymer is depolymerized in the DCU 101 into a monomer, such asacetaldehyde. In this embodiment, the water also flows through the DCU101, without any chemical reaction with the polymer, the monomer or thecatalyst. However, due to the low pressure effects in the DCU 101 at3-12 psia, partial evaporation of water (up to 5 wt %) occurs. Theevaporation results in a monomer rich vapor mixture that consists ofA(g), Pa(g), and water vapor. Under the low pressure effect provided bythe blower 104, water, polymer liquid, and the monomer rich vaporstreams continuously exit from the bottom of the DCU 101 entering PSU102 in flow stream 1003.

The PSU 102 and polymerization assembly 200 will operate similarly asdescribed in other embodiments. In the PSU 102, the monomer and watervapor, up to 5 wt %, are separated from the liquid polymer and liquidwater and flow to the blower 104 in stream 1005, then pumped to the PHU201 in stream 1010. Subsequently, water will be in the PHU 201 andstreams 1009 and 1013. The small water content will not alter theoperations of the components other than inhibiting the side reactionthat forms the 2-butenal in the PHU 201.

The polymer rich stream (Pa(l), A(l), and water) exits the PSU 102 inflow stream 1004 to the LST 107. The mixed stream is separated in theLST 107 into the water layer in the bottom and the polymer layer in thetop of the tank. The recovered water and polymer rich stream are thenpumped to the DCU 101 to repeat the cooling cycle of the disclosedtechnology.

FIG. 10 shows the application of this incorporation of water into thesystems of the disclosed technology as applied to the heatpumpembodiment of FIG. 6, operating in a cooling cycle. In this embodimentthe system is composed of two main assemblies: Evaporator Assembly 400and Condenser Assembly 500. Under cooling mode, the heat exchanger 401functions as a depolymerization cooling unit. The heat exchanger 401 isin liquid communication with a PSU 402, a paraldehyde liquid pump 404, a3-way valve 405, a water liquid pump 410, and an LST 409. The automaticcontrol valve 407 controls the flow of the depolymerization productsdirected to the PSU 402 in stream 2003. In this operating mode, the heatexchanger 501 of the condenser assembly 500 operates as thepolymerization heating unit, in liquid communication with a 2-way valve408 and a three-way valve 503. A paraldehyde and water mixture in stream2007-a is introduced into the depolymerization unit 401. The mixtureundergoes an endothermic depolymerization and evaporation process,drawing heat from stream 2001 and decreasing its temperature to that ofstream at 2002. The water in stream 2007-a does not react inside 401,but experiences partial evaporation. Stream 2005 consists of avapor-liquid mixture, rich in acetaldehyde; its flow from the DCU 401into the PSU 402 in stream 2003, and its flow rate is controlled byvalve 407. The PSU 402 separates the streams 2003 and 2008 (from thePHU) into a vapor stream 2005, rich in acetaldehyde, and a liquidparaldehyde and water stream 2004. As hereinabove described, the LST 409separates the paraldehyde and water in stream 2004, into a liquid waterstream 2009 and a paraldehyde stream 2012. The liquid pumps 404 and 410control the paraldehyde and water flow rate, respectively. The blower,compressor or vacuum pump 502 generates a pressure difference betweenthe evaporator assembly 400 and the condenser assembly 500, by which thewater vapor is condensed into liquid water. The liquid polymer andliquid water also flow to the PSU 402. Furthermore, it facilitates theevaporation of stream 2005 and its flow into PHU 501 where it undergoesa polymerization and condensation process. Heat generated in PHU 501 isdissipated to the system surroundings into stream 2010, resulting in adischarge air stream 2011. The liquid products from the polymerizationprocess in PHU 501 are discharged through stream 2008, its flow rate iscontrolled by one 2-way expansion valve 408. After undergoing anexpansion process, stream 2008 flows into the PSU 402 and undergoes thepreviously explained separation process.

FIG. 11 shows the application of this incorporation of water into thesystems of the disclosed technology as applied to the heatpumpembodiment of FIG. 7, operating in heating mode. As indicated by streams2006-b and 2007-b, the flow direction in the system is changed. Underthis configuration the heat exchanger 401 functions as the PHU and theheat exchanger 501 as the DCU. The flow direction is modified using two3-way valves 405 and 503. The liquid paraldehyde and water are reroutedby 405 and co-fed into the DCU 501 in stream 2007-b. The heat exchanger501 draws heat from air stream 2010 decreasing its temperature to thatof stream 2011. The depolymerization products exit the DCU 501 in stream2008 into the PSU 402. The blower, compressor or vacuum-pump 502 drawsthe vapor rich stream 2005 from the PSU 402. The vapor stream out of theblower, compressor or vacuum-pump 502 is redirected by one 3-way valve503 into stream 2006-b and enters the heat exchanger 401. Polymerizationreaction and condensation processes take place in the heat exchanger401, dissipating heat into stream 2001 and increasing its temperature tothat of stream 2002. The dissipated heat is also used in the evaporationprocess in the PSU 402.

Although not shown, water may be similarly incorporated into theembodiments of the disclosed technology shown in FIGS. 2-4 and 8.

In another embodiment of the disclosed technology, as shown in theschematic process flow diagram of FIG. 12, an uninterrupted coolingcycle with a single combined polymerization and separation unit (CPSU)601 is provided. In this embodiment, a single combined polymerizationand separation assembly 600 consists of a CPSU 601, a blower 602, and apressure regulating device 603, such as a valve, an orifice, a pump, orany combination of these devices. The assembly 600 is configured toreplace the polymerization assembly 200 and the PSU 102 shown in FIGS.2-5 and 8-9 with a single unit to polymerize the monomer rich vapor and,using the heat from the polymerization process, to separate the monomerrich vapor from the polymer rich liquid. Although not shownspecifically, this single unit polymerization and separation assemblymay be used with the cold energy storage assembly and technology asshown in FIGS. 2-4 and herein described.

The configuration of the CPSU 601 provides for both the polymerizationof the monomer gas (by means of, for example, a liquid-to-liquid heatexchanger, having a polymerization chamber) and the separation of themonomer rich vapor from the polymer rich gas (by means of, for example,a vapor-liquid separator having a separation chamber). A tube-and-shellevaporator may function as the CPSU in the disclosed technology. In sucha configuration, the shell portion of the CPSU is similar to PSU 102 ofprior embodiments, functioning as a vapor-liquid separator andseparation chamber designed to receive the inlet monomer rich gasmixture from the DCU 1003 and the polymer rich liquid mixture 1009 afterpolymerization, and separate them into the monomer rich vapor 1005(greater than 80 wt % monomer, and in some embodiments greater than 90wt % monomer) and the polymer rich liquid 1004 (greater than 80 wt %polymer liquid, and in some embodiments greater than 90 wt % polymer)under the previously disclosed pressure (3-12 psia) and temperature(40-60° C.) conditions. The bottom of the CPSU 601 has a polymerizationchamber designed similar to a liquid-to-liquid heat exchanger, with anacid based catalyst in the tube flow portion of the reactor. In thisconfiguration, the monomer rich vapor 1010 from the shell portion of theCPSU is fed, at an increased pressure of between about 10-25 psia, intothe tubes, polymerizing the monomer as it flows over the acid basedcatalyst. The resulting polymer rich mixture 1009 is returned to theseparator/shell portion of the unit, and the remaining monomer isseparated from the polymer rich liquid and returned to thepolymerization portion of the unit, by means of line 1010. While theprocess has been described by the example of a tube and shell heatexchanger, other heat exchanger configurations may be suitable forpurposes of these reactors of the disclosed technology. In someembodiments, such as where excess monomer generates heat in excess ofthe heat required for separation, fans or other means to expel theexcess heat from the CPSU may be integrated with the system; in otherembodiments, where heat generated by the polymerization of the monomeris necessary for the separation process as herein described, then theCPSU may be wrapped in heat insulation, designed as double walled tanks,or may otherwise be insulated to maintain the heat within the CPSU.

In this embodiment of FIG. 12, when operating in a cooling process boththe polymer and the water are pumped from the LST 107 to the bottom ofthe DCU 101, entering the DCU as a combined stream of water and polymer.In this embodiment the polymer is pumped in stream 1008, and the wateris pumped in stream 1012, wherein the water pumping rate is controlledat 1-10 wt % of the polymer flow rate to prevent excess accumulation ofwater in the DCU 101. Similar to FIG. 9, and as in previously describedembodiments of the disclosed technology, the polymer, such asparaldehyde, is depolymerized in the DCU 101 into a monomer, such asacetaldehyde, and the water flows through the DCU 101, without anychemical reaction with the polymer, the monomer or the catalyst. Thepolymer, monomer and water mixture is removed to the separation portionof the CPSU 601 in stream 1003. However, due to the low pressure effectsin the CPSU 601 at 3-12 psia, and 4-45° C., partial evaporation of water(up to 5 wt %) occurs. The resulting monomer rich vapor mixture thatconsists of A(g), Pa(g), and water vapor is removed from the separationportion of the CPSU 601, in stream 1005.

The monomer rich vapor exits from CPSU 601 in stream 1005, similarly asdescribed in other embodiments, and flows into the tube flow portion ofthe reactor at the bottom of the CPSU 601 under the influence of blower602. The monomer is polymerized over an acid catalyst to produce apolymer rich liquid (Pa(l)), with less than 100% conversion, under atemperature range of 26-55° C. and pressure ranges from 10 to higherthan 14.7 psia. The small amount of water content will not alter thepolymerization operation other than inhibiting the side reaction thatotherwise forms the 2-butenal during the polymerization process. Theheat produced under the polymerization reaction is transferred to themixtures within the shell side of the CPSU 601, facilitating theseparation of monomer vapor from polymer liquid. The polymer richmixture in flow stream 1009 is returned back to the CPSU 601 shellpotion for further separation of remaining monomer gas. Packing (such asmetal packing) may be included in the CPSU to facilitate separation ofthe liquid and the vapor in the shell portion of the CPSU. The pressuredifferential between the stream 1010 (greater than 10 psia) and stream1009 (3-12 psia) is regulated by blower 602 in the path of flow streams1005 and 1010 and by a pressure regulating device 603, similar to thehereinabove described embodiments. The heat transferred from thereaction into the shell side of the CPSU causes the mixture within theshell portion, under the applications' pressure conditions (3-12 psia),to further vaporize the monomer gas from the polymer rich liquidmixture, and recycle it through stream 1005 for re-polymerization. Amore concentrated polymer rich liquid stream (>80 wt % polymer, and insome embodiments >90 wt % polymer) and water is then expelled from theCPSU 601 to LST 107, at stream 1004, to facilitate the independentfeeding of both water at feed stream 1012 and paraldehyde polymer atfeed stream 1008 into the DCU, as described in other embodiments.

In the embodiments shown in FIGS. 2-13, the DCU 101 can be configured toincrease the flow rate of feed stream 1008 significantly so the reactionis limited by reaction equilibrium with little monomer vaporization.Under the applications' pressure (3-12 psia) and temperature (4-45° C.)conditions, but with a faster flow rate, polymer will be depolymerizedto a liquid mixture of polymer and monomer with or without water (insome embodiments, this mixture may be around 80 wt % polymer). Theoverall polymer conversion in terms of kg monomer produced per kgpolymer feed will be lower due to lack of monomer vaporization in theDCU, however, the overall cooling rate can be maintained because morepolymer can be pumped into the DCU 101 to compensate for the low polymerto monomer conversion rate. The liquid polymer-monomer mixture stream1003 then flows to the PSU 102 or CPSU 601 to continue the separationprocess, wherein a portion of the monomer will vaporize under theconditions of the PSU/CPSU, as herein described for other embodiments,and will separate from the liquid mixture, which vapor portion will bere-polymerized in the PHU 201 or 501, or the CPSU 601, as hereindescribed. Unvaporized monomer in the liquid mixture is recycled throughthe LST or PST and to the DCU.

The flow rate in these embodiments will vary based upon the application(amount of cooling needed); preliminary testing and estimations showed aheat flow rate of 0.7 kW per 1 liter/minute polymer flow rate at a DCUcooling temperature of 8° C., based upon a reaction heat of 110 kJ/molor 833 kJ/kg, wherein the polymer is paraldehyde. The density ofparaldehyde is 1 kg/liter, and the estimated polymer-monomer conversionin these calculations is 5%.

The potential impact of the dry-cooling system of the disclosedtechnology for cooling power plant condenser cooling water is theperformance penalty imposed by air cooling when ambient temperatures arehigh. The performance penalty is the result of higher temperaturecooling water returning to the condenser, raising condenser saturationpressure and lowering turbine output. In contrast, wet cooling allowscooling systems to operate at wet bulb temperature levels. Under similarcondition, the wet bulb temperature is lower than the dry bulbtemperature, by an average of 3-5° C. As a result of this fundamentalthermodynamic limitation, the use of prior art dry cooling systemsresult in an average of 2% loss of power output from the steam turbinecompared to wet cooling operation, and up to 10% reduced powerproduction under high ambient temperature conditions.

The systems and methods of the disclosed technology eliminate the powerproduction loss (performance penalty) due to high ambient temperaturespresent in traditional dry cooling technology. Further, the disclosedtechnology is a closed system, with zero water dissipation to theatmosphere, while providing cooling below ambient dry bulb temperature.The disclosed technology thereby provides a transformational anddisruptive development compared to the traditional cold storagetechnologies, such as ice storage and room temperature phase changematerials (PCMs). The system of the disclosed technology, with itspractical 1,363 kJ/kg heat storage capacity, has 4 times the heatstorage capacity of ice and 7 times the capacity of PCM systems, anduses significantly less energy than comparable technologies (see Table2). These qualities lead to a smaller and cost effective cooling system.

TABLE 2 Comparison of Heat Capacity and Energy Use Phase PureTempParaffin Salt Ice Disclosed Change (Entropy Hydrates Storage TechnologyMaterial Solutions) Source Vegetable Petroleum Minerals Water PolymerAverage 170-270 130-170 140-170 334 up to 1,330 Heat Storage, kJ/kgEnergy Use n/a n/a n/a ~1.3 ~0.04 in kWh/kWh Stored

With prior art technology, the dry bulb ambient air temperature and thesecond law of thermodynamics set the lower limit of the steamcondensation temperature within an air-cooled condenser. High ambienttemperature excursions penalize power plant power output performance.The systems of the disclosed technology provides an innovative solutionto cool below ambient dry bulb temperature limit and address temperatureexcursions. The novel approach of combining depolymerization andre-polymerization to create a cycle that pumps heat from a power plantcooling system to the atmosphere effectively eliminates extensive wateruse and lowers the amount of energy required to provide cooling waterfor efficient turbine energy production. Likewise, certain reversiblechemical reactions which produce endothermic and exothermic reactionswithin the condenser and ambient temperature ranges may be used in lieuof the depolymerization and polymerization reactions hereinabovedescribed. When standalone or combined with current dry coolingtechnology (with other technology operating at ambient temperatureswithin 5° C. higher than the power plant design point), the system ofthe disclosed technology has the potential to make thermoelectric powerplants independent from the nation's water supply infrastructure,operate with high efficiency, and conserve significant water resourcesfor use in the agricultural, municipal, and industrial sectors.

The system of the disclosed technology can also serve other industrialcooling applications such as closed cooling loops for gas turbine inletair cooling, lube oil cooling, steam cracker cooling for polymerproduction, and intercooling loop for large industrial compressors, aswell as other applications as hereinabove described.

Furthermore, the system and methods of the disclosed technology may becoupled with the thermal management system (TMS) for directed energysystems such as high energy lasers (HELs). As hereinabove discussed,coolant flow rate range and temperature range in the TMS may be designedto ensure the temperature of the pump diodes and other HEL componentsare maintained close to the optimal temperature, enabling the HEL tooperate continuously. The disclosed technology cycle, systems andmethods, and the embodiments and configurations herein described, can beused to provide highly efficient cooling to this coolant, ensuring itreturns to the directed energy components within the designedtemperature and flow rate ranges of the HEL.

As shown in the embodiment of FIG. 14, a dry-cooling module useful inabsorbing heat from coolant in a directed energy system is provided. Aswith the other embodiments of the disclosed technology herein described,in this embodiment the module a depolymerization assembly 100 includinga DCU 101, in fluid communication with a polymerization assembly 200,including a PHU 201. The DCU has an acid based catalyst disposed withina heat exchanger, and receives streams of polymer at line 1008 and waterat line 1012, and further provides for the TMS coolant to cycle throughthe DCU at lines 1001, 1002. As in other embodiments, contact of thepolymer (e.g., paraldehyde) over the catalyst within the DCU convertsthe polymer into a monomer (liquid or gas, as hereinabove described) inan endothermic reaction. This endothermic reaction draws heat from thecoolant cycling through the DCU. A stream of monomer is withdrawn fromthe DCU at line 1003 and provided to the PHU at line 1010 forre-polymerization. A blower 104 may be incorporated into the system influid communication with the DCU and the PHU to withdraw the monomerfrom the DCU, and convey the monomer to the PHU. In some configurations,as hereinabove described, the monomer resulting from the contact of thepolymer over the first catalyst within the DCU is primarily a gas; inother configurations the monomer resulting from the contact of thepolymer over the first catalyst is primarily a liquid.

The PHU 201 of the present embodiment also comprises a heat exchanger,wherein a second acid based catalyst is disposed within the PHU and thePHU receives the monomer at line 1010. As hereinabove described, thefirst acid based catalyst and the second acid based catalyst may be thesame catalyst. Flow of the monomer over the second acid based catalystconverts the monomer to the polymer in an exothermic reaction, and thePHU expels a stream of the polymer at line 1009 for conveyance to theDCU. Heat is expelled at 1014 from the PHU to the ambient environment ata heat transfer surface. In some embodiments the PHU heat exchangerconsists of multiple finned tubes, with ambient air being blown acrossthe surface of the finned tubes. The fins on the tube increase heattransfer surface area and allow efficient heat rejection from the PHU tothe atmosphere. A fan can be configured to either blow or pull airacross the PHU for efficient heat removal at 1014.

A PSU 102 may be incorporated into the system, in fluid communicationbetween the DCU and the PHU. The PSU may include a PSU heat exchangerand a heat source, wherein the PSU receives from the DCU the stream ofmonomer at line 1003, which stream may also include a portion of thepolymer. Heat is transferred from the heat source to the stream ofmonomer to further separate the monomer and the polymer, and the PSUexpels the monomer to the PHU at line 1005. The coolant from the HPE mayalso cycle through the PSU at lines 1006, 1007 as the heat source of thePSU. The PSU may further receive from the PHU the stream of polymer atline 1009, which stream may also include a portion of the monomer, andexpels the polymer for conveyance to the DCU at line 1004. A pressureregulating valve 106 is used to control the amount of mixture from PHU201 to PSU 102 so that the pressure difference between the two units isproperly maintained at the ranges described hereinabove.

In some embodiments as hereinabove described and depicted in otherfigures (e.g., FIG. 8), a second PSU may be incorporated into the systemin fluid communication between the PHU and the DCU. The stream ofpolymer (which may also include a portion of the monomer) may bedirected to the second PSU instead of the first PSU, and the coolant mayalso cycle through the second PSU allowing heat from the coolant to betransferred to the stream of the polymer liquid and the monomer liquid,to further separate the polymer from the monomer. The second PSU maythen expel the polymer for conveyance back to the DCU and the monomerback to the PHU.

The PSU and PHU may also be configured to facilitate heat transfer fromthe PHU to the PSU as herein described and shown in other figures (e.g.,FIG. 12), wherein the flow of the monomer over the second acid basedcatalyst in the exothermic reaction in the PHU is the heat source of thePSU. In this configuration, the PHU may be positioned within the PSU. Insome embodiments, the PHU may include one or more tubes, the PSU mayinclude a shell, and the tubes of the PHU may extend through an interiorof the shell of the PSU.

As shown in FIG. 14, water may be cycled through the module. In thisconfiguration, the DCU is configured to receive water at line 1012, andthe endothermic reaction of the contact of the polymer over the catalystwithin the DCU causes at least a portion of the water to vaporize intowater vapor, and the DCU expels the water vapor with the monomer to thePHU. The exothermic reaction of the contact of the monomer over thecatalyst within the PHU is unaffected by the presence of water, otherthan inhibiting the side reaction that otherwise forms the 2-butenal,and the PHU expels the water with the polymer for conveyance back to theDCU at line 1009. In this configuration, the system may also include anLST 107 in fluid communication between the PHU and the DCU, to separatethe polymer from the water, and independently convey the polymer and thewater to the DCU at lines 1013, 1008 and 1011, 1012, respectively.Further, excess water may be removed from the DCU by stream 1015, andreturned to the LST 107 for recycling through the system (the waterhaving a different density than the polymer, allowing for removal of thewater separate from the liquid polymer). As in certain otherembodiments, the coolant may cycle through the PSU 102 positioned influid communication between the DCU and the PHU. In this configurationthe PSU receives from the DCU the monomer and water vapor (which streamalso comprises a portion of the polymer) at line 1003, and a stream ofpolymer and water (and a portion of the monomer) from the PHU at line1009, and heat from the coolant cycling through the PSU is transferredto the monomer, water vapor and polymer received by the PSU to furtherseparate the monomer from the polymer. The PSU then expels the monomerto the PHU at line 1005 and the polymer and water for conveyance to theDCU at line 1004.

By these and similar configurations and as hereinabove described anddepicted in the embodiment of FIG. 14, the system and methods of thedisclosed technology can cycle the HEL TMS coolant through the DCU 101(by means of lines 1001, 1002) and the PSU 102 (by means of lines 1006,1007), the module absorbing heat from the coolant in the DCU and the PSUbefore it is cycled back through the directed energy system.

A plurality of pumps are configured throughout the module to control thecycle and enthalpy change of the coolant as it cycles through themodule, as well as the energy drain of the module on the system.Specifically, the polymer feed pump 103, the water co-feed pump 108, theblower 104 and the coolant pump 302 which cycle the polymer/monomer andthe coolant through the system of the disclosed technology may have anadjustable volumetric flow rate to control and optimize the coolantenthalpy change and the energy drain of the components on the system.The operation of these control components may be controlled eithermanually by an operator, or automatically by a programmable logiccontroller (PLC), or both, based upon a volumetric flow rate signalreceived by the component. Further, a Proportional, Integral, Derivative(PID) control may be integrated with the system to monitor and controlany or all of these components. Adjustment of the operation of thesecomponents allows the coefficient of performance (COP) of the system tobe maximized, for example, while maintaining the coolant temperature andflow rate in the range specified for the directed energy components.

For example, increasing the speed of the polymer pump 103 increases theliquid polymer flow rate in stream 1008 into the DCU 101, the conversionrate of polymer to monomer within the DCU 101, and the net cooling thedisclosed technology cycle provides to the entering coolant in stream1001, resulting in the coolant exiting at a lower temperature in stream1002. With the increased liquid polymer flow, the blower 104 outputshould also be increased, decreasing the pressure in the DCU 101, andthereby increases the conversion percentage of polymer to monomer withinthe DCU 101. All of these increases in the polymer flowrate and theblower 104 output will require increase in the flowrate of stream 1015.Similarly, increasing the coolant pump 302 speed increases the exitingcoolant flow rate in stream 3001 and the net cooling transferred fromthe disclosed technology cycle to the directed energy components 301. Ata certain threshold, the coolant pump's ability to transfer cooling tothe directed energy components may be limited by the output of the DCU101. This increased speed of the pumps 103 and 302, and draw of theblower 104 also increases the electrical draw of the components, andresults in a decrease in the system's COP. Further, the speed of theco-feed pump 108 may be controlled such that the water introduced to DCU101 in stream 1012 is a fixed percentage by volume of the liquid polymerfeed to the DCU 1008, or it may be controlled as a variable percentage.Therefore, optimizing the speed/draw of these components to providesufficient cooling to the coolant with as little energy as possible isdesirable to maintain continuous operation of the HEL.

Manual or automatic control of the pumps, blower, and stream 1014 mayoptimize the cooling capacity to provide effective cooling to thecoolant when needed, and will thereby impact the COP. Increasing thesystem cycle cooling capacity beyond design point will certainly reducethe COP. In this case, increasing system cycle cooling capacity is doneby increasing power to system cycle components (103, 108, 104) toincrease the flowrate in streams 1008 and 1012 allowing increaseddepolymerization, and the flowrate in stream 1010 allowing for increasedvaporization of the monomer. The polymerization of the increased monomerflowrate requires increased flowrate of stream 1014. To meet the newcooling demand, power to coolant pump 302 will increase. The increase insystem cooling capacity will be done by increase in electric draw of thesystem cycle. Because increasing system cooling capacity is always lessthan the energy spent in increasing system cycle electric draw, systemcycle COP will decrease.

While manual input or system-specific design may control the speed andfunctionality of the module control components and the TMS coolant pump,using a PLC and PID in the control system would allow the system toautomatically calculate and/or control the pump cycle and coolant pumpto optimize COP within the system's parameters. This control system mayinclude an optimization algorithm tailored to the specific directedenergy equipment and the cycle components.

To facilitate this optimization, various sensors may communicateoperating conditions to the control system. For example, as shown inFIG. 15, temperature sensors such as thermocouples 305, 307, pressuresensors 304, 308, and flow meter 306, may be inserted into the coolantstreams 3001 entering and 1001 exiting the directed energy components,as well as thermocouples 112, 115, pressure sensors 111, 116, and flowmeters 113, 114 in the dry cooling module liquid polymer line 1008entering the DCU and the monomer line 1003 exiting the DCU. Measurementsfrom these sensors may be communicated to the control system and enablethe heat transfer rate of the system to be calculated so thatadjustments may be made to the cycle control components and the coolantpump to achieve optimal performance. For the same purpose, powertransducers or amperage sensors 110, 109, 117, 118, 303, may beinstalled on cycle components (103, 108, 104), stream 1014 and thecoolant pump 302 to measure and communicate to the control systemcomponent power use. This current data of all measured power use coupledwith the calculated heat removed may then be used to calculate the COPof the HEL cooling system, over a period of time, as follows:

${COP} = \frac{{Total}\mspace{14mu}{Heat}\mspace{14mu}{Removed}\mspace{14mu}{from}\mspace{14mu} 301}{{Total}\mspace{14mu}{Electric}\mspace{14mu}{Energy}\mspace{14mu}{Used}}$

If available, the control system may also receive signals representingmeasured directed energy conversion efficiency or beam strength of theHEL as additional optimization parameters. In this case, the impact ofthe disclosed technology cycle components (and the coolant pump on theseparameters) can be considered on the overall operation of the HEL. Sincethe directed energy components usually consume significantly more energythan the associated cooling system, the control system may be programmedto seek to maintain less than optimal operation of the dry coolingmodule cycle components and coolant pump to gain optimal efficiency forthe directed energy components. Such an approach may result in moreeffective total electricity use and possibly decrease the time on targetrequired by the directed energy system.

The control system can be used to operate the dry cooling cycle of thedisclosed technology, monitor performance, and enable the user toincrease or decrease the cooling output by adjusting operation ofprocess equipment and control valves.

In operation, as shown in FIGS. 16-18, a PLC-based control system with auser interface is coupled with any or all of the polymer pump 103, thewater pump 108, the blower 104, and any fan or other component of thedry cooling module, as well as the directed energy system's coolant pump302, each of which may have an adjustable output, such as controlled bya variable frequency drive, adjusting the components output as specifiedby an input signal from the control system. The input signal may be a0-10 VDC control signal provided by a microcontroller, data acquisitionhardware, or custom circuitry. National Instruments hardware and LabViewsoftware, for example, can be used to construct a PLC-based controlsystem useful in the disclosed technology. FIG. 16 shows a section of aLabView block diagram, which enables a user to control twoproportionating valves in the dry cooling cycle. The block diagramenables automatic control over these valves, opening or closing themusing a 0-10 VDC signal in response to a sensor. The block diagram alsoincludes a manual override where the user can force the valve into acertain position, and finally safeties are included to restrict theoutput to the valve to stay within the 0-10 VDC range to protect thevalve in case of user error. This type of control can be extended to thepolymer pump, water pump, blower, and any fan or other component withvariable output in the dry cooling module.

The user interface, such as shown in FIG. 17 and generated in LabView,may display information to the user, such as: valve controls and PIDsettings, process equipment control and PID settings, and sensormeasurements. For example, FIG. 17 shows sensor measurements from thedry cooling cycle including: key temperatures throughout the system,water and polymer flow rates obtained by flow transmitters, pressures inthe DCU, PSU, and PHU obtained by pressure transducers, float levelswitches to determine the fill level of the DCU and storage tanks,wet/dry sensors to detect the presence of co-feed or polymer in the PSUand PHU, conductivity switches to discern between water and polymer inthe DCU, PSU, and storage tank, and power measurements obtained by powertransducers for the fan, blower, and total system power. These sensorsprovide an informed user with the operating state of the dry coolingcycle. Then, through the Equipment Control tab in FIG. 17, the user caninstruct LabView to adjust the input signals to the previously describedprocess equipment. Control of the dry cooling system operation may alsoinclude alarms and other configurations, such as shown in FIG. 18.

Using the afore-referenced technology, a method for a dry-cooling cycleuseful in absorbing heat from coolant in a directed energy system isalso provided. In this method, in a first heat exchanger through whichthe coolant flows, a polymer is depolymerized in an endothermicreaction, thereby drawing heat from the coolant and producing a monomer;the monomer is withdrawn from the first heat exchanger. A second heatexchanger then polymerizes the monomer, producing the polymer, and thepolymer is delivered back to the first heat exchanger. In this method, athird heat exchanger may be provided to receive the monomer from thefirst heat exchanger and the polymer from the second heat exchanger, andthe monomer and the polymer may be further separated, using, forexample, the coolant as a heat source, and once separated the polymer isdischarged to the first heat exchanger and the monomer is discharged tothe second heat exchanger. In some embodiments, water may be cycledthrough the first and second heat exchangers with the polymer andmonomer, respectively.

The method may include adjusting the speed of any number of pumps in thesystem to optimize the amount of heat withdrawn from the coolant or theCOP of the system, as hereinabove described, which adjustment may bemanual or automatic, based upon pre-determined target values and currentoperating conditions as sensed throughout the system.

The invention claimed is:
 1. A dry-cooling module useful in absorbingheat from coolant in a directed energy system, the module comprising: adepolymerization cooling unit (DCU) in fluid communication with apolymerization heating unit (PHU), the DCU comprising a DCU heatexchanger and a first acid based catalyst disposed within the DCU,wherein the coolant cycles through the DCU and the DCU receives a streamof a polymer; wherein contact of the polymer over the first catalystwithin the DCU converts the polymer into a monomer in an endothermicreaction; wherein the endothermic reaction draws heat from the coolantas the coolant cycles through the DCU; and wherein the DCU expels astream of the monomer; and the PHU comprises a PHU heat exchanger,wherein a second acid based catalyst is disposed within the PHU and thePHU receives the monomer; wherein flow of the monomer over the secondacid based catalyst converts the monomer to the polymer in an exothermicreaction; and wherein the PHU expels the stream of the polymer forconveyance to the DCU.
 2. The dry-cooling module of claim 1, wherein themonomer resulting from the contact of the polymer over the firstcatalyst within the DCU is primarily a gas.
 3. The dry-cooling module ofclaim 1, wherein the monomer resulting from the contact of the polymerover the first catalyst is primarily a liquid.
 4. The dry-cooling moduleof claim 1, further comprising a blower in fluid communication with theDCU and the PHU, wherein the blower is designed and configured towithdraw the monomer from the DCU, and convey the monomer to the PHU. 5.The dry-cooling module of claim 1, wherein the polymer is paraldehyde.6. The dry-cooling module of claim 1, wherein the first acid basedcatalyst and the second acid based catalyst are the same.
 7. Thedry-cooling module of claim 1, the system further comprising a firstpolymer separation unit (PSU) in fluid communication between the DCU andthe PHU, wherein the PSU comprises a PSU heat exchanger and a heatsource, wherein the PSU receives from the DCU the stream of monomer,which stream also comprises a portion of the polymer, wherein heat istransferred from the heat source to the stream of monomer and theportion of the polymer to further separate the monomer and the polymer,and wherein the PSU expels the monomer to the PHU.
 8. The dry-coolingmodule of claim 7, wherein the coolant also cycles through the PSU asthe heat source of the PSU.
 9. The dry-cooling system of claim 7,wherein the PSU further receives from the PHU the stream of polymer,which stream also comprises a portion of the monomer, and wherein thePSU expels the polymer for conveyance to the DCU.
 10. The dry-coolingsystem of claim 7, further comprising a second PSU in fluidcommunication between the PHU and the DCU, wherein: the second PSUreceives from the PHU the stream of polymer, which stream also comprisesa portion of the monomer, wherein the coolant also cycles through thesecond PSU and heat from the coolant is transferred to the stream of thepolymer liquid and the monomer liquid, to further separate the polymerfrom the monomer; and wherein the second PSU expels the polymer forconveyance back to the DCU.
 11. The dry-cooling module of claim 7,wherein the PSU and PHU are configured to facilitate heat transfer fromthe PHU to the PSU, wherein the flow of the monomer over the second acidbased catalyst in the exothermic reaction in the PHU is the heat sourceof the PSU.
 12. The dry-cooling module of claim 11, wherein the PHU ispositioned within the PSU.
 13. The dry-cooling module of claim 12,wherein the PHU comprises one or more tubes, the PSU comprises a shell,and the tubes of the PHU extend through an interior of the shell of thePSU.
 14. The dry-cooling module of claim 1, wherein the DCU furtherreceives water, and wherein the endothermic reaction of the contact ofthe polymer over the first catalyst within the DCU causes at least aportion of the water to vaporize into water vapor, and wherein the DCUexpels the water vapor with the monomer, wherein the PHU receives thewater vapor with the monomer, and wherein the PHU expels the water withthe polymer for conveyance to the DCU.
 15. The dry-cooling system ofclaim 14, the system further comprising a liquid to liquid separator influid communication between the PHU and the DCU, to separate the polymerfrom the water, and independently convey the polymer and the water tothe DCU.
 16. The dry-cooling system of claim 14, the system furthercomprising a polymer separation unit (PSU) in fluid communicationbetween the DCU and the PHU, wherein: the PSU comprises a PSU heatexchanger, wherein the coolant cycles through the PSU heat exchanger,wherein the PSU receives from the DCU the monomer and water vapor, whichstream also comprises a portion of the polymer, wherein heat from thecoolant is transferred to the monomer, water vapor and polymer receivedby the PSU, to further separate the monomer from the polymer, andwherein the PSU expels the monomer to the PHU.
 17. The dry-coolingsystem of claim 14, wherein the PSU further receives from the PHU thepolymer, a portion of the monomer and water, and wherein the PSU expelsthe polymer and the water for conveyance to the DCU.
 18. A method for adry-cooling cycle useful in absorbing heat from coolant in a directedenergy system, the method comprising the steps of: in a first heatexchanger through which the coolant flows, depolymerizing a polymer inan endothermic reaction, thereby drawing heat from the coolant andproducing a monomer; withdrawing the monomer from the first heatexchanger; in a second heat exchanger, polymerizing the monomer,producing the polymer; and delivering the polymer to the first heatexchanger.
 19. The method for a dry-cooling cycle of claim 18, furthercomprising the steps of: in a third heat exchanger through which thecoolant also flows, receiving the monomer from the first heat exchangerand the polymer from the second heat exchanger, and further separatingthe monomer from the polymer, using the coolant as a heat source;discharging the polymer to the first heat exchanger; and discharging themonomer to the second heat exchanger.
 20. The method for a dry-coolingcycle of claim 18, further comprising the step of cycling water with thepolymer and monomer through the first and second heat exchangers.
 21. Adry-cooling module useful in absorbing heat from coolant in a directedenergy system, the module comprising a depolymerization cooling unit(DCU) in fluid communication with a polymerization heating unit (PHU),wherein the DCU comprises a DCU heat exchanger and a first acid basedcatalyst disposed within the DCU, and the PHU comprises a PHU heatexchanger and a second acid based catalyst disposed within the PHU;wherein the coolant cycles through the DCU by means of a coolant pump;wherein the DCU receives a stream of a polymer by means of a polymerpump; wherein at least one of the coolant pump or the polymer pump hasan adjustable volumetric flow rate based upon the a volumetric flow ratesignal received by the pump; wherein contact of the polymer over thefirst catalyst within the DCU converts the polymer into a monomer in anendothermic reaction, which endothermic reaction draws heat from thecoolant as the coolant cycles through the DCU; wherein the DCU expels astream of the monomer to the PHU; wherein flow of the monomer over thesecond acid based catalyst in the PHU converts the monomer to thepolymer; and wherein the PHU expels the stream of the polymer forconveyance to the DCU.
 22. The dry-cooling module of claim 21, whereinthe system further comprises a temperature sensor to measure thetemperature of at least one of the coolant or the polymer in the system,and transmit signals representing the measured temperature, over time,to a user interface; wherein the user interface further comprises adisplay which displays data visible to a user based upon the measuredtemperature signals; and wherein the volumetric flow rate signal isgenerated by the user interface based upon input by the user received atthe user interface.
 23. The dry-cooling module of claim 21, wherein theDCU further receives water by means of a water pump, wherein theendothermic reaction of the contact of the polymer over the firstcatalyst within the DCU causes at least a portion of the water tovaporize into water vapor, and wherein the DCU expels the water with themonomer; wherein the PHU receives the water vapor with the monomer, andwherein the PHU expels the water with the polymer for conveyance to theDCU; and wherein the water pump has an adjustable volumetric flow ratebased upon a volumetric water flow rate signal received by the waterpump.
 24. The dry-cooling module of claim 21, further comprising apolymer separation unit (PSU) in fluid communication between the DCU andthe PHU, wherein the PSU comprises a PSU heat exchanger and a heatsource, wherein the PSU receives from the DCU the stream of monomer,which stream also comprises a portion of the polymer, wherein heat istransferred from the heat source to the stream of monomer and theportion of the polymer to further separate the monomer and the polymer,and wherein the PSU expels the monomer to the PHU; and a blower in fluidcommunication with the PSU and the PHU, wherein the blower is designedand configured to withdraw the monomer from the DCU and the PSU, andconvey the monomer to the PHU, and wherein the blower has an adjustablevolumetric flow rate based upon a volumetric blower flow rate signalreceived by the blower.
 25. The dry-cooling module of claim 21, whereinthe system further comprises a temperature sensor to measure thetemperature of at least one of the coolant, the polymer, the monomer,the DCU or the PHU, and transmit signals representing the measuredtemperature, over time, to a programmable logic controller; wherein thevolumetric flow rate signal is generated by the programmable logiccontroller based at least upon the measured temperature signals.
 26. Thedry-cooling module of claim 25, wherein the system further comprises apressure sensor to measure the pressure of at least one of the DCU, PHUor PSU, and transmit signals representing the measured pressure, overtime, to a programmable logic controller; and wherein the volumetricflow rate signal is generated by the programmable logic controller basedfurther upon the measured pressure signals.